Chain saw



FIG. 1 is a left side view of the ornamental appearance of the chain saw;

FIG. 2 is a right side view of the chain saw shown in FIG. 1;

FIG. 3 is a front view of the chain saw shown in FIG. 1;

FIG. 4 is a rear perspective view of the chain saw shown in FIG. 1; and,

FIG. 5 is a front perspective view of the chain saw shown in FIG. 1, with a bar and chain attached thereto.

Any surfaces of the design not shown, including interior or bottom surfaces, form no part of the claimed invention. Moreover, the subject matter shown in dashed lines, including the bar, chain and mechanical fasteners, also forms no part of the claimed invention. 

I claim the ornamental design for a chain saw, as shown and described. 